>> reporter: then, nicole corbett, sabrina's social-worker case manager, testified about a strange call, admitted his marriage to lisa was in trouble and said they were considering divorce. >> what was your reaction to that statement? >> i was surprised. i didn't know they were even considering splitting up or divorce. >> reporter: kevin, she said, asked whether, in a divorce, he would be able to take sabrina with him as opposed to her staying with lisa. >> i just thought it was a little odd that he wanted to take a 17-year-old girl alone in a home with just him. >> reporter: prosecutors next showed jurors cell phone activity. more evidence, they said, that indicated kevin and sabrina were having an affair. >> kevin was texting sabrina way more than he was texting his wife? >> substantially more. >> reporter: within a two week period, kevin and sabrina texted and called each other almost 1500 times. that compares to just 200 calls and texts between kevin and lisa. prosecutors then turned jurors attention to kevin's behavior after lisa's murder. david strunk was one of kevin's close frie